How Civilizations Collapse

Environmental degradation

If our society were to succumb to the onslaught of climate change, it wouldn’t be the first to do so. Studies have shown a correlation between the declines of ancient civilizations and periods of significant climate change. The Harappan civilization is believed to have collapsed after a loss of the monsoon rains, and the New Kingdom of ancient Egypt, the Akkadian Empire, and the Maya all suffered eventual collapse following centuries-long dry periods.

If you broaden the scope to include general environmental decline, the correlation with the collapse of civilizations gets even more striking. The Mesopotamians gradually brought ruin on themselves through the salinization caused by their massive irrigation system, leaving their doleful lamentation, The Curse of Akkad, to tell us how their fields “produced no grain.”

The Maya, too, were brought down not just by drought but overexploitation of their land, and the same seems to have been true for the Anasazi civilization of the American southwest.

In his book, Collapse: How Societies Choose to Fail or Survive, Jared Diamond describes the poignant example of Easter Island where the first human arrivals colonized a fertile, forested haven and then proceeded, over centuries, to destroy every tree on the entire island.

The implications for our current civilization are immediately apparent. In addition to climate change, we’re facing the myriad environmental pressures chronicled in the previous chapter arising from exponential growth in consumption.

However, some who have studied the collapse of earlier civilizations point out that environmental pressures alone, no matter how severe, are not enough to cause a society to collapse. Rather, they say, it depends on how the society responds to these problems.

One anthropologist, Joseph Tainter, notes that in the American southwest, although environmental degradation led in one instance to collapse, in another case it led to the society becoming more complex. “If a society cannot deal with resource depletion,” Tainter ponders, “then the truly interesting questions revolve around the society, not the resource. What structural, political, ideological, or economic factors in a society prevented an appropriate response?”

Tainter’s grand theory of collapse

Intent on answering this question, Tainter extensively studied different civilizations in history, and published his conclusions in a work called The Collapse of Complex Societies. Tainter offered something approaching a grand theory of collapse describing a generic life cycle that applied, in his view, to every complex society including our own.

At their core, Tainter explains, societies can be understood in terms of energy flows. If a society is fortunate to discover a new source of energy, it will naturally grow in size and complexity as it exploits that energy. The source of energy can vary considerably. It can arise from a new technology, such as the irrigation systems of Mesopotamia, or be the collective energy of conquered nations forced to submit to a military power such as the Roman Empire.

As a civilization gets more complex, it needs ever more energy to maintain its growth, and will generally keep doing what it’s done successfully in the past, such as build more irrigation channels or conquer more nations. Tainter describes this as a society’s investment in complexity. However, after the first easy pickings, the next steps in the society’s growth become more difficult and costly, offering more miserly returns.

At a certain point, the society’s return on investment in complexity peaks, and it finds itself spending increasing amounts of resources for ever more meager returns. In effect, as the society gets more complex, it finds itself having to run harder and harder just to stay in the same place.

The problems keep getting bigger, requiring ever more costly solutions, which add to the society’s complexity, in turn requiring even more energy than before, causing a new round of problems that become ever more insurmountable. In this downward spiral, it becomes increasingly difficult for regular citizens to maintain the lifestyle they were used to, frequently leading to social unrest, which further undermines the society’s resilience. “With continuation of this trend,” Tainter concludes, “collapse becomes a matter of mathematical probability, as over time an insurmountable stress surge becomes increasingly likely.”

The collapse of the Roman Empire

The Roman Empire presents the best documented – and dramatic – example of Tainter’s model. Tainter tells how, as it expanded, Rome would conquer new territories and appropriate the spoils, in the form of agricultural surplus, treasure, and slaves, causing an infusion of wealth. However, after each conquest, the Empire incurred new costs to administer, garrison and defend the province. How did they pay for this? By conquering another territory for another one-time wealth infusion.

By the first century CE, the Roman Empire had expanded so far that maintaining it was draining Rome’s wealth, while new territories were becoming increasingly difficult to conquer. Rome’s return on investment in complexity was turning negative. How did its leaders respond? By gradually debasing Rome’s currency, the denarius, reducing its silver content with copper and thereby artificially increasing the money supply.​With this strategy, Rome’s leaders essentially kicked their problems down the road for later generations to deal with. “The inflation that would inevitably follow,” writes Tainter, “would tax the future to pay for the present, but the future could not protest.” Eventually, the denarius became worthless and the empire was on the brink of collapse. Taxes were raised beyond the peasants’ ability to feed themselves, villages dwindled, people fled to the cities, and by the time Rome itself was ransacked in 476 by Germanic tribes, it was a virtual non-event to much of the empire which had already been devastated by Rome’s own policies.